Weld Pins, Weld Studs and Cuphead (or “mini-Cup”) Insulation Pins. At Melparts ,we know that getting work done fast and with reliability is really important to most jobs, and we have ways to help with that. The fast and practical application of Capacitor Discharge StudWelding. A process often called “CD” welding for short. Installing Fasteners with “C.D.” welding can be very portable and uses “everyday”, one-hundred-and-ten-volt power. In addition ease-of-use, CD Welding Systems have: simple parts work quickly and can be used on thin metals to apply a range of Fasteners. The process of Capacitor Discharge welding occurs in a series of 4 rapid steps: Contact Ignition Placement of the Fastener and “Completion” of the Weld.